Anecdotal at best.
For everyone saying it ('Kich Ich' or any reef-safe treatment for Marine Ich) has worked there are 6 more who say it doesn't work.
In controlled experiments you need:
1) Independent, microbial identification of the disease organism;
2) Verification that the infection is underway;
3) A control group (infected but not treated - near identical fishes)
4) Prescribed treatment;
5) Independent, microbial verification that the disease organism is gone.
Then. . .
6) Repeat this in multiple tanks; different labs/homes; different locations.
Most of the 'reef safe' treatments for Marine Ich (Cryptocaryon irritans) don't provide the above information.
I worked years in the early '70's with a scientific approach to find alternative treatments for MI. Copper and hyposalinity were the only treatments that worked more than 99% of the time.
Though I'm not trying to impugn ravenr, I would still need the date from the above 5 steps as a minimum to believe it. The significant and amazing part of the above steps is that they are not all that difficult to go through, yet the very large, (wealthy?) manufacturers of these reef safe products either don't or won't provide the results and data of such work.
What most of these products contain is a single or multiple group of materials which have shown to have a negative affect on MI, or even fool the theronts, but which, in clinical studies, have failed to totally wipe out the disease. The disease has one very vulnerable part of its life cycle -- the free swimming, infecting theronts. A variety of materials can kill theronts in the lab, but in a reef aquarium there are so many variables, with everyone's reef being a little bit different, that those same chemicals are compromised into having little or no effect. A label that says 'contains [material] which has shown effective against [MI]" can be true, yet the treatment fail for the above reasons.
We all want to find the shortcut. A short cut has been sought for more than 70 years now by some of the best minds in the scientific community, and if something existed to rid marine food fishes of this !@#$ organism, the aquaculture industry and the private and public large aquariums would be all over it like 'white on rice.' But guess what they use?
I truly wish I had something more encouraging to say on this. :sad1: